The present invention relates to a method and an arrangement for reproducing a stereophonic audio signal in a space, particularly in the passenger compartment of a motor vehicle, with loudspeakers for reproducing acoustic signals being arranged at a plurality of positions in the space.
The brochure xe2x80x9cProgramm ""97xe2x80x94Sound und Fahrvergnxc3xcgen pur. Mobile Kommunikation von Blaupunktxe2x80x9d ""97xe2x80x94 Sound and Driving Pleasure Through Mobile communication from Blaupunkt published by the firm Blaupunkt describes reproduction devices for audio signals automotive sound systems to which four loudspeakers for reproducing an audio signal can be connected. A first loudspeaker, for example, is being disposed in the door trim panel of the driver-side door, a second loudspeaker is mounted in the door trim panel of the front-seat passenger door, and a third and forth loudspeakers are arranged in the left side and right side of the rear shelf. The levels of the reproduced audio signals for the left and the right stereo channels may be so matched to one another by a balance controller that, for example, a natural stereo aural impression results for the vehicle driver.
Thus, in the case of the conventional automotive sound systems, it is possible to produce a three-dimensional sound effect when reproducing stereophonic audio signals along an imaginary longitudinal axis through the passenger compartment of a motor vehicle. This longitudinal axis is shiftable by the balance controller between the two sides of the vehicle. Therefore, a three-dimensional sound effect can be produced, for example, on the driver side of a motor vehicle, but not equally for the driver side and the front-seat passenger side.
In this context, the term three-dimensional sound effect means that a listener located on the indicated longitudinal axis picks up different signals from the left and right loudspeakers, and thus receives a spatial sound impression, though generally with pronounced in-head localization, head localization means that the listener receives a three-dimensional sound effect, however he fixes the position of the acoustic sources as being close to or in the head.
Therefore, with conventional automotive sound systems, it is not possible to produce a natural stereo aural impression when reproducing stereophonic audio signals in a motor vehicle, or a balanced three-dimensional sound effect for the driver side and the front-seat passenger side in a motor vehicle.
In contrast, the method and the arrangement of the present invention have the advantage that an equally natural aural impression, with the feeling of a natural distance of the acoustic sources, can be produced when reproducing a stereophonic audio signal within an enlarged listening zone inside the space to be exposed to sound, particularly both on the driver side and on the front seat passenger side inside of the passenger compartment of a motor vehicle. In this context, the impression of a natural distance of the acoustic sources corresponds to the aural impression of a listener who is actually sitting in a concert hall and locates the position of the instruments according to their actual position. For that purpose, it is also necessary that, for the listener, the impression be given of fixing the position of the acoustic sources outside of the space to be exposed to sound. This is made possible by the method and the arrangement of the present invention.
It is particularly advantageous that, given suitable control of the loudspeakers arranged in the space, the enlarged listening zone for which a natural stereo aural impression results includes the largest part of the space to be exposed to sound, thus, for example, the rear seat within the motor vehicle as well.
A further advantage is that the control for controlling the individual loudspeakers arranged in the space conditions the signals for each individual loudspeaker with respect to amplitude and phase. Thus, the control also takes into account the reflections occurring within the space to be exposed to sound, i.e., their influence on the natural stereo aural impression within the listening zone.
The arrangement and method of the present invention are easily implemented by using digitalized audio signals and a digital signal processing, e.g., in the form of a digital signal processor.
Furthermore, it is advantageous that, when using the arrangement and the method, respectively, of the present invention in a motor vehicle, the signal corrections necessary for the individual loudspeakers can be prepared as a data record for various vehicle types, and thus for variably configured passenger compartments, and can be activated during the final assembly of the vehicle.